1. Field of the Invention
The present invention relates to a grommet for protecting a wire harness to be passed through, for example, a through hole formed in a car body panel.
2. Description of Related Art
FIG. 5 is a cross-sectional view exemplifying a related grommet. FIG. 6 is a cross-sectional view illustrating a manner of assembling the grommet shown in FIG. 5.
One such a related grommet 1 has been proposed (see, e.g., Patent Document 1), in which a cap-like elastic expansion portion 3 is concentrically and integrally molded with the periphery of the central shaft 2, as illustrated in FIG. 5. When the grommet 1 is assembled to a body panel 10, the grommet 1 is inserted into a through hole 12 of the body panel 1 by being pushed thereinto in the direction of arrow A, as illustrated in FIG. 6. Then, the elastic expansion portion 3 interferes with and is elastically deformed by the body panel 10. Subsequently, the elastic expansion portion 3 is elastically restored from the deformed state. Thus, the grommet 1 is fit into the through hole 12 of the body panel 10, as shown in FIG. 5.
The related grommet 1 is configured so that the elastic expansion portion 3 has a predetermined lap width L1 with respect to the diameter D1 of the through hole 12 of the body panel 10 (e.g., L1=D1+3 mm) so as to prevent the grommet 1 from being disengaged from the body panel 10 when the wire harness 5 inserted into the central shaft 2 is pulled in the direction of arrow B. Consequently, the related grommet 1 ensures a high holding force.
Patent Document 1: JP-A-06-231642 (Paragraph No. [0023], FIG. 1)
However, in a case where the lap width L1 of the elastic expansion portion 3 is increased to assure the high holding force of the grommet 1, a high insertion force is needed when the grommet 1 is inserted into the through hole 12 of the body panel 10. Thus, the assemblability of the grommet 1 is degraded.